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Tesi etd-10042021-221406


Tipo di tesi
Tesi di laurea magistrale
Autore
VISINTINI, FEDERICO
URN
etd-10042021-221406
Titolo
Thermodynamics of a DWave 2000Q quantum annealer
Dipartimento
FISICA
Corso di studi
FISICA
Relatori
relatore Prof. Giovannetti, Vittorio
correlatore Dott. Campisi, Michele
Parole chiave
  • quantum thermodynamics
  • quantum annealing
  • quantum information
  • DWave
Data inizio appello
25/10/2021
Consultabilità
Tesi non consultabile
Riassunto
In this work, we study the thermalization process of the DWave 2000Q QPU, a commercially available quantum annealer equipped with more than 2000 superconductive qubits. The original work presented in this manuscript consists of two separate but connected contributions, namely a claim of an effective coupling between the qubits and the environment and a measurement of a stochastic work extraction.It is well known that despite the best efforts to keep the machine isolated from the environment, both thermally and electromagnetically, the quantum processor is best described as an open quantum system. We present a description of the QPU in termsof effective degrees of freedom, according to the Lindblad master equation formalism.By adopting the reverse annealing schedule, we sampled the effective coupling be-tween the qubits and the bath, proposing a new model for the environment and theinteraction which explains all behavior observed in the machine, except for the casewhen the device energy spectrum presents small gaps, late during the anneal. We leavethis class of problems for future study to investigate.In the last part of the work we propose and carry out a procedure, in which thesystem is driven out of equilibrium and statistical fluctuations occur in the oppositedirection to what prescribed by the second principle of thermodynamics, which remainvalid on average. Measurements are carried out in different regimes on one and twoqubit problems. Results are compared to expected theoretical behavior and simulated evolution in the machine using the coupling proposed in the first part.
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